OK folks.  This is an update from my original post.  Thanks to all for the suggestions.  I have not yet tried all of them but I hit the major ones.  I have done the following:

Replaced spark plugs using correct heat range and gap
Ignition wires show 5400 ohms resistance end to end
New injector in questionable cylinder
Swapped injector wires with adjacent cylinder
Swapped ignition wire with adjacent cylinder
Replaced the distributor as mine had a loose connector
Compression tests great
Adjusted valve clearance per Bentley Manual

The engine starts and runs great when cold.  After 2-3 minutes, it randomly missfires on right rear cylinder.  I can drive it around the block but it is obviously down on power.  It tends to fire on all 4 if I take the RPM above 4500 while shifting from 1st to 2nd and 2nd to 3rd gears.  35 MPH speed limit keeps me from trying other gears during test drive.  This is the darndest problem I have ever run up against.  Have I missed anything?

Thanks
Tom